How long does it take for depo to get out your system? and can I be pregnant now ?

Basically , I got pregnant n got abortion and I got the IMPLANON ROD. 1yr of non stop bleeding. Removed the IMPLANON Mar/14 and got the Depo Mar/14. I bleed then it stop. My 2nd shot I got in July/14. I was bleeding on/off until sept. My 3rd shot was in Oct , didn't go. I bleed on and off until Jan,Feb I was back to having normal periods, I was cramping,clots you know... Now my period engine is back running normal. I figure things should normal. I am having lots of unprotected sex with my fiance... And it has been 1 YEAR today AUG/15... My last shot July/14. Why am I not pregnant yet. Im so worried that everything stopped working. Someone help ?